i. Technical Field
This invention pertains generally to the field of medical instruments, and more particularly to an improved laryngoscope blade for aiding a medical practitioner performing endotracheal intubation, particularly during difficult intubations.
ii. Technical Background
During patient medical care, often it is necessary to insert an endotracheal tube for respiratory support of a patient in distress. For example, a patient under general anesthesia is unable to maintain unassisted respiration, and an endotracheal tube connected to a respirator will be inserted in the patient's trachea to perform respiratory support. Endotracheal intubation also is performed frequently on critically ill patients who are unable to breathe effectively on their own, and on patients who are unable to protect their airway from vomitus from the stomach.
Endotracheal intubation procedures, which may be orotracheal wherein the endotracheal tube is inserted through the mouth of the patient, or nasotracheal wherein the endotracheal tube is inserted through the nose of the patient, are a routine part of the daily practice of an anesthesiologist. For other health care professionals, such as paramedics and other physicians, the procedure is less routine and performed less often. For all who perform the procedure, even under ideal conditions, intubation can be highly stressful. When intubation is performed to support a non-breathing patient, brain damage or death resulting from inadequate supply of oxygen can occur within four minutes. Clearly, intubation must be completed rapidly.
During endotracheal intubation, the glottic opening, which is defined by the glottis or vocal cords and surrounding structures, must be identified, so that the tube is correctly inserted through the glottic opening and into the trachea. Positive identification of the glottic opening minimizes the possibility of esophageal intubation and the potential of hypoxic brain damage.
A laryngoscope is the instrument used to assist intubation, and typically includes a handle and detachable blade disposed at near right angle. Numerous different types of blades are available, including straight and curved types. Most practitioners tend to favor one or the other of the common blades, and will use it in the vast majority of procedures. The blade is inserted into the mouth of the patient, holding the mouth in a fully open position and the tongue against the floor of the mouth. The epiglottis frequently is elevated, either through direct contact by the laryngoscope blade or indirectly by raising hypopharyngeal tissues. Under normal circumstances, this will expose the epiglottis and glottic opening to allow direct observation by the practitioner who sights along the laryngoscope blade. A light on the blade illuminates the visual field.
For perhaps one intubation of every one-hundred, anatomical variance in the patient causes difficulties. In some patients, the glottis is located anteriorly, placing the glottic opening out of the normal field of view. In other patients, such as those having small mouths or mandibular joint dysfunctions, the mouth can not be opened sufficiently for the desired positioning of the laryngoscope blade, and the field of view presented will be limited to the regions of the oropharynx. Occasionally, these conditions are anticipated, and adequate precautions can be taken. Often, however, the condition is not recognized until the intubation procedure has been started. In a patient having elective surgery, such a condition can pose a life-threatening situation for an otherwise healthy patient.
Drastic steps may become necessary to complete the intubation procedure before brain damage or death results from oxygen deprivation. Forcing the laryngoscope blade deeper into the hypopharynx may result in excessive pressure being applied against the teeth of the patient, causing the teeth to crack or break. After beginning the procedure with standard instruments, it may become necessary to use specialized instruments to complete the procedure. Preparing and switching instruments wastes much of the limited time available for intubation, and results in even the most experienced practitioner being forced to use instruments with which he is less experienced. Further, some such specialized instruments, such as flexible fiber-optic devices, can not be used on infants because of size.
Intubation under abnormal conditions becomes highly stressful for everyone involved, including the most experienced practitioners, which may further reduce efficiency and performance.
In my aforementioned U.S. Pat. No. 5,263,472, I disclosed an improved laryngoscope blade having a telescope affixed to the blade. The telescope includes an eyepiece near the laryngoscope handle, a barrel extending along the blade and a front lens near the distal end of the blade. This improved blade has been found to be of great assistance in the vast majority of difficult intubations. However, in some of the most difficult intubations, even the improved blade of my previous invention has not adequately revealed the glottic opening. On curved blades, the fixed telescope is widely spaced from the upwardly curved tip of the blade, and may make the overall end structure of the blade too large for proper insertion. The front lens, fixed in position can be fouled by tissue or secretions. The fixed telescope on each blade makes the blades expensive.
In my aforementioned co-pending U.S. patent application Ser. No. 08/156,003, I disclosed a telescopic laryngoscope blade in which the endoscope is adjustable in position relative to the blade, and can be moved forward and reward relative to the blade tip. While my telescopic blade works well for optimally positioning the endoscope for viewing the glottic opening, under some conditions, especially when the endoscope is extended relatively far forward, tissue and secretions can foul the objective lens, hampering viewing.